Strange Mini-Asteroid Born by Huge Space Rock

Below:

Next story in Space

Astronomers have discovered a new kind of asteroid a strange
mini-world with a unique and violent history that could reveal
more clues about the early solar system.

The asteroid, called 1999 AT10, is a miniature space rock born
when a collision blasted it out of its rocky parent Vesta, which
is the
second-largest asteroid in the solar system. The
mineralogical composition of 1999 AT10 suggests that unlike many
other asteroids, it did not originate from the outer rocky crust
of its parent asteroid Vesta, but from the deeper layers
underneath. Until now, no asteroid like it has ever been seen.

The discovery of 1999 AT10 could help determine the thickness of
Vesta's crust, and reveal details about its internal structure,
scientists say. With a body approximately 326 miles (525
kilometers) wide, Vesta is believed to be the only remaining
protoplanet from the early phase of our solar system.

Strange, new (mini) world

The new asteroid was discovered by researchers from the
University of North Dakota and from the Max Planck Institute for
Solar System Research in Germany, using NASA's Infrared Telescope
Facility on Mauna Kea, Hawaii.

The
asteroid Vesta is unique. Unlike main belt asteroids, which
orbit the sun between Mars and Jupiter, Vesta has a
differentiated inner structure. A crust of cooled lava covers a
rocky mantle and a core made of iron and nickel quite similar to
the terrestrial planets Mercury, Venus, Earth and Mars.

Scientists consider this onion-like asteroid to be a protoplanet,
a relic from an early phase of planet formation more than 41 /2
billion years ago. All other protoplanets in the solar system
either accumulated to form full-blown planets or broke apart due
to violent collisions, researchers said.

There's more support for this scenario: Vesta seems to have
experienced a huge impact, as can be seen from a large crater on
its southern hemisphere, researchers said. [ Photo
of Vesta's crater ]

These so-called Vestoids a group of
asteroids with a composition similar to that of Vesta were
most probably created due to this impact. Since some meteorites
that were found on Earth consist of rock similar to Vesta's
mantle, scientists suspect that this collision also hurled
material from deep within the asteroid into space. But until now
there was no source in the form of near-Earth Vestoids for these
meteorites with Vesta's mantle composition.

Near-Earth asteroid 1999 AT10 fills this gap. Researchers
were able to analyze the infrared radiation that 1999
AT10 reflected into space and compare its characteristic
spectral fingerprints with those of Vesta. Apart from the
calcium-rich mineral wollastonite, the measurements primarily
point to the presence of the iron-rich material ferrosillite.

"These materials can be found in Vesta's mantle and crust,"
Andreas Nathues of the Max Planck Institute said in a statement.
'"However, the ratio is decisive." In the case of 1999
AT10, the concentration of iron is clearly lower than in any
known Vestoids. "This all points to 1999 TA10 having
originated from the interior of Vesta."

More clues of asteroid Vesta?

The newly discovered body allows astronomers to form new insights
into its parent asteroid, researchers said.

Models of Vesta's surface based on observations made by the
Hubble Space Telescope suggest the south pole crater is about 16
miles (25 km) deep at the most. The new mini-asteroid now
suggests that this would be the maximum possible thickness of
Vesta's outer crust.

In order to reconstruct the processes that led to the formation
of planets more than 4.5 billion years ago, scientists need to
determine the thickness of Vesta's layers as precisely as
possible. Only this makes it possible to calculate from which
material mixture the protoplanet was made and thus which
materials were present when the solar system formed.